Catalyst for the preparation of formaldehyde

 

(57) Abstract:

The invention relates to the petrochemical industry, in particular to catalysts for the preparation of formaldehyde by the oxidation of natural and associated petroleum gas. The aim of the invention is to increase the selectivity of the catalyst due to a change in the qualitative and quantitative composition of the catalyst. This objective is achieved in that the oxidation catalyst is used molybdoenzymes catalyst supported on silica gel in the amount of 0.15 to 1 wt. % and the oxidation is carried out at T 650oC when the content of methane in methane-air mixture of about 30. %.

The invention relates to the petrochemical industry, in particular to catalysts for the preparation of formaldehyde by the oxidation of natural and associated petroleum gas.

A known method of producing formaldehyde by oxidation of natural gas with oxygen at elevated temperature in the presence of the oxide catalyst in a fluidized bed using as catalyst molibdenovokislogo catalyst supported on silica gel, of the following composition: MoaWbOcwhere a 1-2; b is 1, c is determined by the valency and the process 000 h-1the conversion of methane to 13.2-33 when selectivity 46-65,6

The disadvantages of this method are low selectivity to formaldehyde and the use of highly concentrated molibdenovokislogo catalyst (more than 30) supported on silica gel.

The aim of the invention is to increase the selectivity of the catalyst due to a change in the qualitative and quantitative composition of the catalyst.

This objective is achieved in that the oxidation catalyst used molybdoenzymes catalyst supported on silica gel in the amount of 0.15 to 1 wt. and oxidation is carried out at a temperature of 650oC when the content of methane in methane-air mixture of about 30.

Example 1. The preparation of the catalyst. The estimated number of paramolybdate ammonium (NH4)6Mo7O244H2O dissolved in distilled water upon acidification of the solution with hydrochloric acid (pH of 4-4 .5). The temperature of the solution 60-70oC. Then add the required amount of nitrate zirconium Zr(NO3)4to achieve a molar ratio of Mo:Zr 10:1. In all experiments, this ratio is constant, changing only the total concentration data salts in solution to achieve the 0.15-1 vpityvayut crushed silica gel (0.5-1 wt.) at a temperature of 60-70oC. the Solution is evaporated under stirring. The obtained pellets of the catalyst is kept in an oven at 100-110oC. This catalyst is loaded into a solution made of stainless steel (18CR10NITI). The download is 0,72 g (volume 0.5 cm3). The catalyst activated at a temperature of 650 experienceoC when the flow of 1.5 l/h of steam-air mixture with a water content of about 5. within 60 minutes

Example 2. The catalyst is prepared analogously to example 1, except that it contains 0.5 wt. paramolybdate ammonium by weight of silica gel. The catalyst loading to 0.72 g (0.5 cm3). The process is carried out at 650oC, the methane concentration is about 30. the ratio of methane to oxygen 1,8 1 and space velocity of methane-air mixture of 3.7 l/h Output oxidation products is about. CO27,1, CH2O 4,54. Selectivity for formaldehyde 39,0 methane Conversion of 16.3 mol.

Example 3. The catalyst is prepared analogously to example 1, except that it contains 0.5 wt. nitrate of zirconium by weight of silica gel. The catalyst was tested under the same conditions as in example 2. The output of products of oxidation. CO22,6; CH2O 11,0. Selectivity for formaldehyde 83,9 Conversion of methane to 7.6 mol.

Example 4. The catalyst analogously to example 1, only he sod is x, as in example 2. The output of products of oxidation. CO24,9; CH2O 13,0. Selectivity for formaldehyde 72,65 Conversion of methane to 14.3 mol.

Example 5. The catalyst analogously to example 1, except that it contains 0.25 wt. malintencionados catalyst by weight of silica gel. The catalyst was tested under the same conditions as in example 2. The output of products of oxidation. CO22,9; CH2O 19,6. Selectivity for formaldehyde 87,0 Conversion of methane to 9.3 mol.

Example 6.

The catalyst analogously to example 1, only contains 0.5 wt. malintencionados catalyst by weight of silica gel. The catalyst was tested under the same conditions as in example 2. The output of products of oxidation. CO21,2; CH215,7. Selectivity for formaldehyde 92,2 Conversion of methane to 5.7 mol.

Example 7. The catalyst analogously to example 1, except that it contains 1.0 wt. malintencionados catalyst by weight of silica gel. The catalyst was tested under the same conditions as in example 2. The output of products of oxidation. CO25,2; CH2O 15,7. Selectivity for formaldehyde 75,0 Conversion of methane to 9.5 mol.

Proposed for oxidation of methane-air mixture molybdoenzymes catalyst (0.15 to 1 wt.), applied to siliconization to obtain formaldehyde, comprising a compound of molybdenum and silica gel, characterized in that it additionally contains a compound of zirconium in a mass ratio of 10 to 1 if the content of molybdenum compounds and zirconium compounds of 0.15 to 1% by weight of silica gel.

 

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7 cl, 2 dwg, 1 tbl, 11 ex

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13 cl, 1 tbl, 24 ex

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17 cl, 3 tbl, 25 ex

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5 cl, 7 tbl, 7 ex

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9 cl, 1 dwg, 3 tbl, 7 ex

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